A printing method described in Japanese Patent Publication No. 52-41682 is known as a method of transferring a pattern onto a curved surface. In this printing method, a thin film having a pattern previously printed on its surface is let float on a liquid surface with the surface of the printed pattern facing upward, and an object is pressed against the surface so as to sink into the liquid. The pattern is thus transferred onto the object by the liquid pressure. After the transfer of the pattern, the thin film is removed from the surface of the object.
Japanese Patent Publication No. 57-50547 describes a printing method of transferring efficiently a pattern on a curved surface of an object by means of a liquid pressure. In this printing method, a water-soluble base sheet is used in a manner in which the base sheet is let float on a water surface and dissolved in water. An adhesion is sprayed onto a print layer remaining on the water surface after dissolving the base sheet, to form a semi-fluidal printing pattern is thus formed. An object is pressed against the printing pattern, thereby to transfer the pattern onto the surface of the object.
Meanwhile, Korean Patent Application Publication No. 95-17199 describes a printing apparatus which uses a liquid pressure to transfer a pattern onto a surface of an object by sequential steps and an apparatus used in the method. In this printing method, a transfer sheet having a base sheet on which a pattern is printed is let sequentially flow on the water surface in a water tank from a transfer sheet feed. While sequentially flowing the transfer sheet, the base sheet is dissolved. Thereafter, an adhesion is applied thereon and transfer printing is carried out. Together with the method, this Publication describes a printing apparatus provided with a long water tank used in the printing method.
Although the technique described in the Korean Patent Application Publication achieves a technique for mass-production in which a pattern is sequentially transferred to a great deal of objects, a large amount of water is required for the sequential steps including dissolving of base sheets, resulting in a new problem that a long time is required for increasing the temperature of water in the water tank so that starting of printing is delayed.
In addition to the above technical problem from the view point of the working efficiency, problems from the view point of saving materials are pointed out from the working side.
That is, according to a conventional printing method disclosed in the Korean Patent Application Publication, separation of a pattern printed on a transfer sheet is carried out in a step after the base sheet of the transfer sheet fed onto the water surface is dissolved and an adhesion is thereafter applied to form a semi-fluidal print pattern. Specifically, the base sheet is dissolved while the transfer sheet is being fed onto the water surface and conveyed in form of a band. After the dissolving of the base sheet, an adhesion is sprayed onto a pattern remaining on the water surface to form a semi-fluidal print pattern, and in this stage, a partition member is inserted from the upside of the water surface to separate the print patter for every area to be used in one time of transfer work.
In this working method, an adhesion is applied to a necessary range for the transfer sheet flowing in form of a band. It is however difficult to insert a partition member exactly at the boundary of the range, and therefore, the adhesion is applied to the range including a slight excessive margin for the partition member to be inserted. The portion corresponding to such a margin cannot be used for transfer to an object and may be said to be waste. Even such a small wasteful portion caused in only one time of transfer leads to enormous waste in the mass-production situation at present. Working fields demand technical developments in eliminating such wasteful margins for the separation member to be inserted. Thus, there is a demand for a technique capable of cutting the sheet into a minimum size necessary for transfer.
Further, since the working method described above requires sequential working while the sheet is flowing on the water surface, it is necessary to perform smooth and adept insertion of a partition member. To achieve manual application of an adhesion and manual insertion of a partition member, smooth and adept skill is required to some extent and is a significant burden for a person in the art. Hence, there is a demand for automation of such operation, and developments must be made as to a technique for cutting the transfer sheet in connection with the automation.
An object of the present invention is to shorten the time required for increasing the temperature of water, which is necessary to dissolve the base sheet, in a printing method capable of performing sequential and efficient printing onto surfaces of mass-products, and in an apparatus thereof.
Another object of the present invention is to eliminate wasteful portions which are conventionally caused when separating a pattern and which cannot be used for transfer, by cutting a transfer sheet before the transfer sheet is fed and reaches a water tank.
The above objects of the present invention and other objects than those described above will be clearly understood from the description of the present specification and from the drawings appended hereto.